The effect of an experimental anhydrous stannous fluoride dentifrice on the acid resistance of dentin smear layers.

To compare the relative performance, in an in vitro assay, of a standard dentifrice (Colgate Cavity Protection) with an experimental anhydrous 0.454% w/w stannous fluoride dentifrice at protecting the dentin smear layer against dietary acids. Artificial smear layers were created on bovine dentin, contacted with slurries of the dentifrices, then exposed to a dietary acid (Coca Cola) for periods up to 10 minutes. Both the stability of the smear layer and tubule occlusion were assessed qualitatively by scanning electron microscopy and confocal laser scanning microscopy. Smear layers treated with the standard dentifrice were removed after 2 minutes of exposure to cola with the smear plugs progressively eroded by longer acid challenges, leaving patent tubules. Treatment with the experimental stannous fluoride dentifrice provided extensive protection of the smear layer against cola for up to 10 minutes, with very few tubules unoccluded.